/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.core.codec;

import org.springframework.core.ResolvableType;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.MimeType;
import org.springframework.util.MimeTypeUtils;

import java.nio.ByteBuffer;
import java.util.Map;

/**
 * Decoder for {@link ByteBuffer ByteBuffers}.
 *
 * @author Sebastien Deleuze
 * @author Arjen Poutsma
 * @author Rossen Stoyanchev
 * @since 5.0
 */
public class ByteBufferDecoder extends AbstractDataBufferDecoder<ByteBuffer> {

    public ByteBufferDecoder() {
        super(MimeTypeUtils.ALL);
    }


    @Override
    public boolean canDecode(ResolvableType elementType, @Nullable MimeType mimeType) {
        return (ByteBuffer.class.isAssignableFrom(elementType.toClass()) &&
                super.canDecode(elementType, mimeType));
    }

    @Override
    protected ByteBuffer decodeDataBuffer(DataBuffer dataBuffer, ResolvableType elementType,
                                          @Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {

        int byteCount = dataBuffer.readableByteCount();
        ByteBuffer copy = ByteBuffer.allocate(byteCount);
        copy.put(dataBuffer.asByteBuffer());
        copy.flip();
        DataBufferUtils.release(dataBuffer);
        if (logger.isDebugEnabled()) {
            logger.debug(Hints.getLogPrefix(hints) + "Read " + byteCount + " bytes");
        }
        return copy;
    }

}
